1. Field of the Invention
The present invention relates to a method for producing a resin composition used for paint. More particularly, the present invention relates to a method for producing a resin composition used for paint which is preferable for improving dispersibility of pigments, thereby improving productivity.
2. Description of the Related Art
Conventionally, paint resin compositions usually include coloring materials such as particular inorganic pigments, organic pigments, or the like, depending on their application. In case of dispersing pigments in a resin composition used for paint, if the dispersibility of the pigments is not sufficient, a paint film obtained is not a good one, and various problems easily occur during coating processes. Further, a deterioration of the quality of the film could be caused.
Especially, in a case of an electrodeposition paint, low dispersibility of pigments easily cause a sedimentation of the pigments in the resin composition used for paint. In order to suppress the sedimentation, an electrodeposition paint bath is provided with a stirrer to keep the electrodeposition paint flow. However, sedimentation of the pigments cannot be completely prevented. During electrodeposition, a part of the settled pigment is deposited on horizontal areas of a material being painted, and this leads to a degradation of an appearance of the paint film in these areas. For example, in cases of a body of an automobile, an outdoor unit of an air conditioner, and the like, more pigments may be deposited on upper surface of horizontal surfaces than on other areas of a material being painted in a electrodeposition bath, and this causes problems in evenness, smoothness and sharpness of the paint film.
An approach to improve dispersibility of pigments in a resin composition used for paint includes changing a composition of the resin composition, such as changing a resin used in the dispersion, and the like. However, changing the composition of the resin composition used for paint itself requires a new confirmation over the long term of properties of the resin composition used for paint.
An object of the present invention is to provide a method for producing a resin composition used for paint which improves the dispersibility of pigments, thereby improving productivity and paint film properties of the resin composition for paint, without changing the composition thereof.
The above-described object of the present invention is accomplished by the following invention.
Namely, a first aspect of the present invention is a method for producing a resin composition used for paint, wherein plural pigments, which compose a resin composition used for paint, is dispersed at an optimal dispersion mixing ratio with resins and solvents, which has been found in advance using Daniel Flow Point Method, and then other components are added thereto to form the predetermined resin composition used for paint.
A second aspect of the present invention is a method for producing a resin composition used for paint wherein the resin composition used for paint is an electrodeposition paint composition.